Lamp with a three-dimensional injection-molded circuit carrier, in particular motor vehicle interior lamp

ABSTRACT

A motor vehicle lamp employs conductor moldings in which conductor tracks extending in three dimensions can be created in the housing. In addition, the conductor moldings enable the integration of lamp connections, switches and lamp mount, as well as reflectors and cooling surfaces directly into the housing and separately inlaid or molded-in plates for contact tracks.

FIELD OF THE INVENTION

The invention pertains to a lamp with a three-dimensional (3D)injection-molded circuit carrier.

BACKGROUND OF THE INVENTION

The existing lamps, in particular interior lamps for motor vehicles,feature a large number of individual parts. These include base plate,circuit board, contact plug, contact bushing, housing covers, reflectorand switch, which are integrated very little within each other.Therefore the lamps must have a complicated assembly from a largernumber of individual parts.

The research alliance for three-dimensional electronic assemblies 3-DMID e.V., in Erlangen, has published a paper in which it is proposed touse three-dimensional structures, such as plastic housings,simultaneously for direct holding and reinforcement of conductor tracksand electronic components. In this case a method has become known forcasting of injection molded conductor moldings in the housing. Theseconductor moldings, which are cast in a "two-shot" injection moldingtechnology with the plastic housing, have the property that theirsurface (in a method comparable to the production of printed circuitboards) can be provided with conductor tracks. The plastics industry hasdescribed metallizable plastics in this regard, which can, for instance,be cast over with an additional, readily flowing, plastic such thatsurfaces of the metallizable conductor molding remain on the surface ofthe entire cast part which can later be metallized and can be used asconductor tracks or contact surfaces.

Therefore the purpose of the invention is to specify a lamp in which theexplained technology can be used and which can be produced in largequantities at low cost by the integration of the components statedabove, and that can be easily assembled.

SUMMARY OF THE INVENTION

In its most basic form, the invention includes a casting in the housingof a lamp, a suitably shaped conductor molding, in which the bracketsneeded for mounting the glow lamp are cast on the housing element. Sincethe brackets are formed by the conductor molding which has ametallizable surface, the glow lamp can be supplied with current, eventhough no additional metallic conductors lead to them, but rather only aconductor track applied to the conductor molding (similar to printedcircuit boards).

The invention can also utilize the metallizability of the plasticsurface simultaneously as a reflector for the glow lamp. Thus, at leasta portion of the conductor molding is formed as a reflector and is castin a single unit with the lamp housing. Thereafter, the reflectorsection is metallized with a metal which is suitable for reflection oflight beams. In this case, we can use chromium, silver or aluminum, forinstance. But other substances are also suitable, provided they havesufficient reflectivity. The stated solution also remains within theframework of the invention, when the conductor molding is formed from aplastic that has a bright color suitable for reflection, such as, white.

The metallized sections are particularly useful when used tosimultaneously perform several tasks. For example, the metallizedsections can be used simultaneously as conductor track to conduct thecurrent to the glow lamp and as a reflector. An additional andsupplemental possibility consists in using the large metal surfacesimultaneously for cooling purposes.

In a combination of features, in which the sections serve simultaneouslyas conductor tracks, in a refinement of the invention, it is recommendedto use the combination of features in which a metallized section isallocated to each of the two contact ends of a preferably elongated glowlamp and supply the needed current to the associated contacts along saidsection. The same result is obtained when the sections are used forinfeed of current to the two brackets in contact with the lamp contacts.

In a further refinement of the invention, the sections employed asreflectors are combined with the property of the brackets clamping theglow lamp. Accordingly, the brackets are formed from the reflectorsections so that lamp housing, reflector, conductor tracks and theclamping brackets form an integrated unit.

As a replacement for or in addition to the assemblies described above,one additional contact or several contacts of a switch can be integratedinto the housing of the lamp, with the moving contact being guided bymeans of an appropriate configuration of the housing itself. But it isalso possible to mold the moving contact directly in a housing as aspring-like protrusion or contact arm, so that only one actuator has tobe moved, whose movement brings the spring-mounted moving contact intocontact with the fixed-position contact. In this manner it is possible,in addition to the above elements, to integrate a switch into thehousing, while at the same time, a protrusion on the contact arm canproject outside the contour of the interior lamp as a manually operatedactuator element.

By means of the conductor molding(s), the plug outlets can be integratedinto the invented lamp by molding to the housing, metallizable(blade-like) protrusions or even metallizable openings which can be usedas contact blades or contact bushings.

Finally, the components formed in the housing of the lamp can beconnected via conductor tracks by means of the conductor molding, saidconductor tracks are configured as metallizable connecting surfacesbetween the elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of the interior lamp with the coverings removed.

FIG. 2 is a cross section through the lamp according to FIG. 1 alongline A--A.

FIG. 3 is a cross section through the lamp according to FIG. 1 along theline B-D-E-F-G-H.

FIG. 4 is a cross section through the lamp according to FIG. 1 along theline C--C.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 shows the housing 1 in which an injection-molded conductormolding is encased in part in a two-shot method by well flowing plasticmaterial. Thus, the conductor molding whose surface can be metallized iscast first. Next, in a second injection molding step for the conductormolding, a flowable plastic coating is applied to all locations whichare not to be metallized. The surfaces not covered by the flowableplastic coating thus form the future current-carrying surfaces, andindividual regions can certainly be electrically isolated, so thatseveral electrically separated conductor tracks are produced. In thiscase, the contour of the conductor tracks is specified by the contour ofthe metallizable regions of the conductor molding. Since during thegalvanizing sic; electroplating! process, given a suitable structure ofthe galvanizing bath, the deposited metal parts will be distributeduniformly onto the metallizable surfaces, in this manner, highlycomplicated, three-dimensional conductor track structures are obtained.Thus it is left to the user to divide either a single conductor moldingduring the second injection process by means of corresponding ridgesinto suitable circuit-regions, or to connect several conductor moldingstogether in a second injection process. FIG. 1 shows the housing 1, inwhich an injection-molded conductor molding 2 is encased in part by anencasing element 3. The encasing element 3 is coated in a secondinjection step around the conductor molding 2 where its surface is notto be metallized. The encasing element 3 thus covers the conductormolding except for the areas to be kept free of metal deposits.

After a subsequent galvanic process, the housing has five electricallyconductive areas which perform different tasks in the switch. Forexample, the regions 4 and 6 form primarily two sections 9 and 10 of anessentially tub-like reflector 11. The two sections 9 and 10 in thiscase are coated with a suitable metal, such as silver or chromium, whichis electrically conducting and highly reflective.

As FIG. 1 and FIG. 2 show, clamp brackets 12, 13 are molded onto thesections 9 and 10; these brackets protrude from the tub 11 and can bebent elastically away from it. Like the surface of the tub, the surfaceof the brackets is coated with a conducting metal, and the tub andbracket are preferably made of the same metal. The contact ends 15, 16of a glow lamp 14 are clamped between the brackets 12 and 13 and arethus electrically connected.

A second tub 17 performs the same task as the first tub 11, with thesurface of the tub 11, 7 sic! facing the viewer being composed of aconductive subsection 18 of the conductive section 10 and the conductivearea 8. The subsection 18 and the conductive area 8 are separatedelectrically by an angled ridge 19 of the encasing element 3, on whichno conductive metal can be deposited during the galvanic process. As apart of the conductive area 6, the subsection 18 is thus electricallyseparated from the conductive area 8. The conductor ends 20, 21 of aglow lamp 23 are electrically connected to the subsection 18 and theconductive area 8. If a voltage is applied to the area 8 with respect tothe subsection 18, then the lamp 23 will light up.

The conductive area 4 features a subsection 24, which is designed as aflat part. The same goes for the conductive area 5. The subsection 24and also a portion of the area 5 are surrounded by a switch wall 25standing perpendicular to them wherein in the conductive area 5 and theconductive area 4 can be guided along the switch wall 25 by means of acorresponding structure of the encasing element 3.

As indicated in FIG. 3, the switch wall 25 can be used simultaneouslyfor mounting a moving switching element 26 (contact bridge), whichelectrically connects or disconnects the subsection 24 with theconductive area 5, depending on the particular setting. The conductivearea 5 and the conductive area 6 run into plug contacts 27, 28. Thus ifwe apply a voltage to the plug contacts 27, 28, then the glow lamp 14will light up, provided the moving switch element makes an electricalconnection of the subsection 24 with the area 5. Thus we obtain, in anintegrated format, an interior lamp in which the glow lamp 14 can beconnected to current by means of plug contacts 27, 28 and a switch andalso the brackets 12 and 13, with the current-carrying areas 4 and 6serving in part also as reflector for the glow lamp.

The same also applies with regard to the subsection 18 and theconductive area 8. Here, too, a switch element 26 is shown by dashedlines and connects a subsection 30 of the area 8 to the conductive area7, and, in turn, to a plug contact 31 associated with it.

The straight ridge 32 of the encasing element 3 performs the sameelectrical separating function as the angled bar 19.

In order to prevent back-cutting, the base of the housing 1 is open atthe height of the first tub 11 and of the second tub 17, so that thenonreflective back sides of the two tubs are readily accessible from theside of the housing 1 turned away from the lamps 14, 23.

The housing 1 features an electrically nonconductive, first perimeterwall 33 and second perimeter wall 34, in which coverings 35, 36 can snapin. From the upper edge of the perimeter walls 33, 34 a perimeteraperture 37 branches off and is shown in cutaway view in FIG. 1, so thatthe blade contacts 27, 28 and 31 are visible.

The invention is based on the principle of shifting the conductor tracksin a lamp to the surface of the lamp housing, and in additionalrefinements, of utilizing the conductor tracks located at the surfacesimultaneously as reflectors, as cooling surface or plug contacts. Forconductor tracks of this kind on the spatial surface of the lamphousing, the use of conductor moldings which are encased in the lamphousing was described above. But for the principle of the invention, theuse of conductor moldings is not compulsory. Rather, the desiredmetallizing of the three-dimensional surface of the lamp housingrequired for the invention can also be achieved by an already knownsemiadditive method, without leaving the framework of the invention. Ina semiadditive method of this kind the following steps take place: Thesurface of the housing is activated and the circuit areas coming intoquestion are coated with electrolytic copper. Next, a photoresist isapplied which is exposed with a spatial mask (3D mask). Next, theexposed area is developed with the photoresist. Subsequently, in aninherently known manner, electrolytic copper is applied and thinned byuse of an etching mask and subsequently the photoresist is removed andthe unneeded copper is etched away.

The conductor tracks obtained according to this known methodconsequently perform the same function as the conductor tracks obtainedby means of the conductor molding. The conductor moldings are preferredin particular, when they are formed from a material which is able toperform additional tasks. For example, this can be the light guide inthe interior of the housing of the lamp or of another component, or itcan have a different coloration compared to the surrounding housingsections, or even a greater transparency than the surrounding housing.The use of the semiadditive method might be recommended in particular ina complex configuration of the conductor tracks.

I claim:
 1. A motor vehicle interior lamp comprising:a lamp housing; areflector disposed within the lamp housing; an injection moldedconductor molding disposed in the lamp housing and having a pair ofclamp brackets separated by a distance suitable for engaging contactends of a glow lamp; and two conductive metallized areas electricallyisolated from each other with each of the conductive metallized areasdisposed over one of the clamp brackets, wherein the conductivemetallized areas define the reflector.
 2. A lamp as claimed in claim 1,wherein the conductive metallized areas are essentially symmetrical andare electrically isolated from each other.
 3. A lamp as claimed in claim1 wherein the conductor molding is cast integral with the lamp housingand two flat parts of the conductor molding are metallized and arefreely accessible from an interior of the housing with the flat partsbeing adjacent and electrically isolated with a movable switchingelement disposed in the housing being selectiveably movable toelectrically connect the two flat parts.
 4. A lamp as claimed in claim1, wherein plug contacts defining a plug for the lamp are fixed to theconductor molding and the conductive metallized areas extend to the plugcontacts.
 5. A lamp as claimed in claim 1, wherein a second glow lamphas two connector lines electrically connected to adjacent metallizedareas.
 6. A lamp as claimed in claim 1, wherein metallized electricconductors are cast into one of the lamp housing and the conductormolding and ends of the conductors are connected to one of themetallized layer and a load and a switch.
 7. A motor vehicle interiorlamp comprising:a lamp housing; a reflector disposed within the lamphousing; an injection molded conductor molding disposed in the lamphousing and having a wide surface section curved in a concave fashion ona first side and being metallized on the first side to define thereflector; and a glow lamp disposed at least in part over the metallizedfirst side.
 8. A lamp as claimed in claim 7, wherein the reflector isconductive and the conductor molding includes a pair of metallized clampbrackets disposed on the first side and oriented to engage contact endsof the glow lamp.
 9. A motor vehicle interior lamp comprising:a lamphousing; a conductor molding disposed within the lamp housing having apair of opposing elastic metallized brackets projecting from the moldingand electrically isolated from each other; and a glow lamp havingcontacts engaged by the brackets wherein a configuration of themetallized brackets is consistent with the use of a semiadditive methodfor metalizing the brackets; wherein the conductor molding forms areflector for the glow lamp.